The B&W height setting is pretty much dependent on what suspension your truck is equipped with. Some, even the F350 have a 2" suspension block while others the more common 4". Also dependent on the spring pack - 2,3 or 4 plus the overload leaf. For my signature 2011 with the heaviest suspension (3 plus overload, 12,000 based on part numbers) and 2" block, I'm in the middle setting and have 6+ inches of bed rail clearance and trailer level.
I guess what I'm saying is that you need to do a trial and error setup using your truck and 5er. I'm also aware that 2015 bed sides are higher then a 2011 in a 4x4 truck
Traveling with my DW Susan, a couple poodlepups and our 2014 Montana High Country 343RL, being towed by a 6.7 2011 F250 CCLB using a B&W hitch and OEM puck system